Control of pyrolytic conversion



y 7, 1930. F. A. HOWARD 1,760,136

CONTROL OF PYROLYTIC CONVERSION Filed May 21, 1923 Patented May 27, 1930 UNITED STATES PATENT OFFICE FRANK A. HOWARD, OE ELIZABETH, NEW JERSEY, ASSIGNOR '10 STANDARD OIL DE- VELOPMENT COMPANY, A CORPORATION OF DELAWARE CONTROL OF PYROLYTIC CONVERSION Application filed Kay 21,

This invention relates to the pyrolytic conversion of hydrocarbons to lower boiling products and will be fully understood from the following description, taken in connection with the accompanying drawin which shows semi-diagrammatically one orm of apparatus contemplated in the invention.

' eferring more particularly to the drawing, the reference character A designates a heating conduit for passage of hydrocarbons and provided with heating means. Such conduit may be of suitable construction, for instance a coil made up of parallel tubes 1 1 with cross-over connections at the ends from tube to tube and row to row to provide a path for consecutive flow. A connection 2 preferably carrying a check valve leads on to a digesting or cracking passageway for approach to equilibrium, in the example shown a drum B, insulated or otherwise suitably provided against heat loss, and from the drum a connecting pipe 3 leads to a vapor separator S, which may advantageously contain also primary condensing means, for example rectifying plates 4 and a collecting pan 5 for the heavier condensate. A vapor line 6 leads from the top of the vapor separator to a final condenser 7 and receiver 8. The feed line 9 for the system connects through a heat exchanger 10, preferably in the top of the vapor separator, and on to the 0011 A.

From the collecting pan 5 apipe 12 leads to an accumulator tank H which is insulated or otherwise suitably provided against heat loss, and a pipe 14 leads through a cooler C to a tank T. A pump P is arranged to draw from the hot tank H or the cold tank T as desired and forward the condensate hotor cold through the pipe 17 from which one branch 18 leads to the inlet to the heatmg 0011 A and another branch 20 leads to the inlet to the drum B.

Thermometers and pressure gauges are located about the system at points desired.

Assuming the plant in operation, with the feed. traversing the heating coil A and the digesting or cracking drum B and the products proceeding to the separator S. the lighter hydrocarbon vapors will pass through the rectifying plates and on out by vapor line 1923. Serial No. 640,492.

6'to the condenser 7 and receiver 8,'while heavier vapors will condense on the rectifying plates and the condensate collecting in condensate may be drawn from the tank T and forwarded through pipe 20' to enter the drum B with the feed, or through the pipe 18 to beintroduced with the feed in the coil A. Various combinations also of these may be employed as desired.

It is thus seen that hydrocarbon products condensed after leaving the cracking passageway and heavier than the final product desired may as a hot orcold condensate or various mixtures from both for the temperature desired, be introduced with the feed into the digesting zone for a quick and convenient modification of the temperature therein as a flexible independent temperature con trol against undesired height of temperature; at the same time such heavier condensates are aiforded an opportunity for further cracking. Wherekeeping the condensate hot, heat is to that extent conserved for the system as a-whole, while thetemperature is yet sufiiciently lower'than that of the digestion zoneto make possible quite a range of control. To the extent that cooler oil is required, it too is conveniently available. Condensate not sent to the digestion zone may be passed into the heating coil, or may be otherwise used as desired.

Preferably, we so operate as to perform a material part of the cracking in the heating conduit or coil, and then finish in the zone which is guarded against temperature loss. In its broader aspects however the invention contemplates introducing into the second or digesting zone heavier condensate derived from the cracking, irrespective of whether only the final portion or all of the cracking is done in such zone.

' cold line the piping of the condensate without the re-' finements of division into hot line and cold line. It will be understood also in general that changes may be made which come within the spirit and scope of the invention.

What I claim is:

1. In apparatus of the character described the combination of a heating condult, a digestin or cracking passageway connected therewith, a vapor separator recelvln A vapors from the digesting passageway an containing rectifying plates and a pan for segregating heavier condensate, a heatretaining tank and a cold tank for recelving said condensate, and connections from sa1 tanks to the digesting passageway and to the heating conduit.

2. In apparatus of the character described, the combination of a heatin conduit, a. heatretaining digesting or crac 'ng passageway connected therewith, a vapor separator, a sole means for withdrawing products of decomposition including vapors from said passageway and discharging them into said vapor separator, cooling and rectifying means in said vapor separator for segregating heavier condensate from the products of decomposition, and connections for introducing the heavier condensate without 'much heat loss directly into the digesting passageway and into the heating conduit.

3. In apparatus of the character described, the combination of a heating conduit, a

digesting or cracking passageway connected therewith and protected against loss of heat, a rectifying tower, a sole means for withdrawing products of decomposition including vapors from said passageway and discharging them into said tower for segregating heavier condensate, means for removing residuum from the tower, and means for introducing such heavier condensate without much heat loss directly into the digesting passageway.

4. In apparatus of the character described, the combination of a heatin conduit, a digesting passageway connecte therewith, a sole means for withdrawing products of decomposition including vapors from said passageway, means for separating tarry residue from said products, means for partially condensing the tar-free product, and re ulable means for introducing such con ensate directly into the digesting assageway.

5. The improvement in t e art of pyrolytic conversion of hydrocarbons to lower boiling products, which comprises heating a stream of the hydrocarbons in a heating zone and it will be underefiectin substantial conversion, then allow-. ing crac 'ng to continue in a digesting zone, passing the cracked products so formed into a tower, removing unvaporized tar therefrom, rectifying the va orized products therein, collecting and wit drawing the condensate from said tower, and passing said condensate into the digesting zone to control the temperature within said zone.

6. The improvement in the art of pyrolgiic conversion of hydrocarbons to lower boi g products, which comprisesheating and materially cracking the hydrocarbons in one zone, then passing the heated hydrocarbons into a digesting zone, withdrawing both liquid and vapor products from the digesting zone in a single stream, separating tarry liquid from the products withdrawn, separating the vapors mto a volatile distillate and a less volatile condensate, and introducing said condensate directly intosaid digesting Z0116.

7. The improvement in the art of pyrolytic conversion of hydrocarbons to lower boiling products, which comprises heating the hydrocarbons to a cracking tem erature, then allowing them to digest, withdrawing the digested product including va ors in a single stream, separating vapors an a tarry liquid therefrom, separatin the vapors into a volatile distillate and a ess volatile condensate, and controlling the digesting temperature by introducing said condensate directly into said digestingzone.

8. The improvement in the art of pyrolytic conversion of hydrocarbons 'to lower boiling products, which comprises heating the hydrocarbons to the desired extent in a heatin zone, then allowing digestion to the desire extent'in a digestion zone, withdrawing the cracked products from said zone through a common line, separating the tarry liquid therefrom, controlling the tem erature of the digestion zone againstundesired rise by introducing condensate from the vapors derived from the digestion, and controlling the temperature of said condensate by cooling a portion of the same before introduction into the digestion zone. 

